Saturday, February 25, 2012

CCARC Wyong Field day 2012

Here's some video impressions of the Wyong field day:

The numbers were clearly up this year, probably a combination of good weather, well organised parking and the success of last year.

I bought a mysterious 250W HF linear amplifier for $25, enjoyed the usual displays from the Home Brew group, Historical Radio Society and the various vendors.

Thanks to the organisers for another fine day out.

Wednesday, February 22, 2012

New printer HP LaserJet P1102w works with OSX & iOS

Our old HP Laserjet 1022n has run for many years but since about the time of Leopard a bug appeared in the driver, that still hasn't been fixed, where it will not print every other page sometimes. This drives me nuts.

For $80, at Officeworks, I purchased an HP Laserjet P1102w and after some messing about it's working really well.

First, there is a firmware update that you must install via USB. Second, the wireless setup, which you need to do via a web page configuration while connected on USB is a little non-obvious - particularly the bit where you click a double arrow button move your wireless network over to the left from the scan list.

An HP employee has put a video on Youtube demonstrating this.

Once on Wifi there is a blue wireless light that should be steady.

Now the printer works great on Lion and finds it's own driver. On Leopard I had to install the driver. Best of all I can print from iOS.

As with many printers these days, a toner cartridge costs more than the printer itself.

Important tip - use a static IP address

The printer goes to sleep quite quickly, which is good, but we've had a frequent problem of computers not being able to connect to the printer. What happens is that the printer's DHCP lease expires and presumably because it's asleep, the computers can't find it until you wake it up.

The fix is to allocate a fixed IP address for the printer. Much better now.

Sunday, February 19, 2012

Softrock Ensemble RXTX with DSP Radio on MacOS X

I've enjoyed the Ensemble RXTX kit build but I'm having a devil of a time with audio under Windows XP. There's not a lot of ham radio software for MacOS but there is an SDR program called "DSP Radio" from Sebastian Mrozek, who has been very helpful in getting me past some problems I ran into.

The instructions with the software are a little brief and so I wanted to capture my working configuration here for future reference.

I'm using a MacBook Air with an Edirol USB audio device for sending and receiving I/Q signals from the Ensemble RXTX. USB control is via TODO which links to DSP Radio.

Plug in the external audio device. Then run the Apple "Audio MIDI Setup" utility (in the utilities folder). Create a new Aggregate Device and add the external USB device and your built-in audio (for your headphones and microphone).

Make sure to set all the devices to the same sample rate.

Set the external USB audio device as the clock source in the popup.

Turn on the Drift Correction checkboxes (called Resample under 10.6) for the built-in microphone and built-in output.

Open the Audio devices window in DSP Radio.

Select the Aggregate Device as both Input and Output.

Open the Configuration window in DSP Radio. (If there is an existing audio configuration there, just leave it and make a new one, then go back later and delete it). Add a new audio configuration.

First make a receive (Rx) configuration. Unfortunately the name of the devices within the aggregate are simply numbered: Input 0, input 1, input 2, input 3; so you need to play around to figure out which is which. I did this by choosing inputs and whistling until I saw my trace on the waterfall - that meant I'd found the microphone.

In my case I/Q from the radio was Input 0 and Input 1 but it may come up differently for you. Play with the Output popups until you get audio through your speaker. For me it was Output 2 and Output 3. Don't worry that the heading says "Output I and Q", that's for transmit. In the receive context it's just audio out to your speaker.

Note that the audio level was very low for me and I had to increase output gain to hear radio signals.

Here's a screen shot with everything working. The second audio configuration line is for transmit.

Transmit configuration is similar. Make a new configuration. Select Tx. Choose the inputs from the microphone channels in your aggregate device. Choose the Output I & Q for the external USB outputs to the radio.

Frequency & TX control via USB

Andrew Nilsson has contributed which talks to the Ensemble RXTX and also links to DSP Radio so that changing the frequency in DSP radio updates the Ensemble. (The file is hosted in a Yahoo group under VK6JBL - you have to join the group to access it unfortunately).

The transmit button in DSP Radio also sets transmit in the radio. Great stuff.

First QSO using PowerSDR under Windows 7

Most of my problems have been sound related under Windows XP so I switched to a laptop running Windows 7 and had much more success. Here's my first contact with VK2HLG - thanks Dave for taking the call.

Sorry about the low receive audio on this one, I'll try to get a better recording next time.

Wednesday, February 15, 2012

Finished and boxed Ensemble RXTX SDR

I'm pleased to report that the build of the Ensemble RXTX kit is complete and I've hacked it into a box.

While there is a purpose built box available, I found something off the shelf that is the perfect width although deeper than really required.

Maybe I could fit rechargeable batteries in there?

I built to cover 20, 30 and 40m and reception is working really well. There is lots of software around but my favourite at the moment is PowerSDR IQ. Note that you need to set the audio jumpers to straight through for this software as it has no reverse I/Q setting.

So far I haven't got transmitting going, partially due to the mystery, to me, of how to control it over USB. As you can see I'm fitting a hardware transmit switch for cases where the software doesn't support TX control over USB.

If I inject a tone into the audio input socket and enable transmit in the test utility I can see that it puts out just under 1W, but for some reason the Transmit button in Rocky 3.7 is dim for me:

Update: Duh, OK, figured this out. Rocky only transmits in CW mode.

I would like to thanks WB5RVZ for the fantastic build notes. These really helped me through the process and covered great detail where it is needed.

A few of the transformers were pretty tight by the time I put the bifilar and secondary windings in them but otherwise all went pretty smoothly. I didn't solder any surface mount devices in backwards on this occasion!

My kit was short 1 10K resister - no big deal (or most likely I've put one in the wrong place...). As the construction notes say:  Even Leonardo DaVinci would have used an ohmmeter on these had he had one! Those reds and browns are really close.

Useful links

I see that KC7IGT has had a QSO, he has a video here:

So I should be able to get this going!

Tuesday, February 14, 2012

Microsoft Office Mac 2011 too buggy on Lion

We mostly use Apple Macs here (except for a Windows XP netbook for some ham radio software). We love Apple's iWork suite but my wife is required to work on documents in Microsoft Word.

She runs Microsoft Office for Mac 2011 on Lion. We have the latest updates of both but her day to day experience is very poor.

The documents she works on are large, hundreds of pages, with track changes enabled and showing lots of history.

Every day, every few hours, Word hangs in some way. Sometimes it shows a black window or a blank dialog box. Mostly we can't quit the program nicely - we must force quit to get out of it.

Word does recover the file without losing too much but it can be distressing for her when deadlines are approaching.

Microsoft do acknowledge quite a few "known issues" but no crashes in Word (only Excel).

This morning, just before heading out the door, we were unable to copy a PowerPoint presentation to a USB key. I know from past experience that Office holds files open even though the window is closed for some reason (no idea if this is still the case but it used to be). We tried to quit all the Office apps, they did appear to exit but when we tried a restart it was prevented by Word.

This software has been around for a long time. People rely on it. I'm embarrassed on behalf of the industry that a user can have such a bad experience every day. LibreOffice is looking very tempting again.

Bad shareholder communications from Westfield

I'm all for going paperless and have switched to paperless notifications of most things, (although I do find myself printing a lot out to hand to my accountant at the end of the year which rather makes me feel like a distributed printing service).

A few Westfield shares means that I get notifications such as the one shown here that just came in.

I noticed that it took rather a long time for my email client to download the email and the "hero" image of "Westfield Sydney City - Feb 12" rendered progressively.

It turns out that the image they embedded in the email, from an email & SMS marketing service called Vision6, is a 6MB image which measures 3495 x 2713 pixels!

It's a lovely image but really, this is abuse of my inbox. Please don't do that.

Friday, February 10, 2012

Ensemble RXTX Software Defined Radio transceiver

On the bench at the moment is the Ensemble RXTX SDR. I've built a Softrock receiver in the past but never tried transmitting so this should be fun. I'm building it to cover 20m, 30m and 40m which seems a pretty useful range.

It's a bit hard to order a Softrock, the site often says "check back soon". I happened to be reading the reddit amateur radio site when someone noticed stock so I got in.

There's still a bit to go but I'm now up to the point where I can try the receiver.

(That photo is from before I was ready to try the receiver). The hairy thing for me with these kits is the soldering of tiny surface mount components but I find that I'm getting better (although probably using too much solder) and also the components seem very robust.

Not too bad eh? (Believe me, it's really tiny).

This model has an Atmel processor which does USB so that the computer can control the frequency and transmit line.

My build has not been all smooth sailing. On receive it was super deaf - turned out I'd wound the wrong T5 and it was attenuating the receiver so much that it made almost no difference when the antenna was connected such that I thought something was unconnected.

There's not many stations on but here's a video of a little reception that sounds pretty good, until my WSPR station transmits and blots everything!

Here's a bit more reception:

The Kodak Zi8 does a pretty good job on these clips I think.

Playing SACD .dff rips on MacOS

Since doing some research on audio quality this week for a RN breakfast panel responding to Neil Young's comments I've been hunting for ways to experience the best quality audio I can get out of my Mac.

I don't have a SACD player but I found some rips in the form of .dff files that contain 1 bit encoded streams at 2.8 MHz. To play these on a Mac you can AudioGate from KORG. It's free but they either want you to have some of their hardware or alternatively use your Twitter account to tweet a little marketing. This seems like a fair deal to me.

The software is written in some kind of cross platform library so it looks pretty weird on the Mac but it works and sounds good. Oddly it claims to be clipping pretty frequently but maybe the track is normalised to use the full dynamic range.

I'm outputting to an Edirol at the highest bit samples and rate I can do.

The software will convert to formats including FLAC:

but as I mentioned they force you to tweet some marketing. Haven't seen this before.


Tuesday, February 07, 2012

HF Loop by Ross 5Z4/VK1UN - T51/VK1UN

Old mate Ross, VK1UN, is currently stationed in Somalia and Mogadishu where he runs WSPR.

In calls via Viber he described an HF loop built from heliax and hose clamps that he's been building and I asked him to send me some photos.

He writes:

"I've been corresponding with Myles VK6ZRY a lot as he has been using a magloop for quite some time now, another notable maploop users on WSPR is Peter DL6NL who has used a loop now for about 2-3 years, maybe earlier (let me check my email). yes, I have email re his loop going back to March 2009, indeed he sent me a photo of it suspended in the horizontal mode over a table inside. Peter typically runs about 200mW on various bands.

I really would like to have a mag loop running on 160m so that I can use WSPR on 160m without having to put up 150m of wire, which is not practical in Mogadishu but a 3m diameter loop supported on plastic water pipe, would be. 

Also the magloop is very narrow in bandwidth and also very sharp in the plane of the loop, one can null out noise sources very easily. 

"I'm beaming to….." takes on a whole new meaning with a magloop, indeed it is bi-directional and, if supported close to the ground, the direction of best radiation is up at, perhaps, 45 degrees from the horizon. Loop currents at resonance are quite high -30 amps in a 3m diam loop on 160m and the voltage at the capacitor can be 5 KV or so and that's why I was seeking a decent vacuum variable, both high voltage and high current. This means I can run up to 75W on a 3m loop with a 4KV capacitor as 100W would mean 5.048KV at the capacitor, still I do not expect to use 75W WSPR too often. 50W, yes! Mind you, a quick calculation for one of three magloop calculating programs shows that even 75W would be 4.372KV at the capacitor! 

There are a few programs that will calculate loop performance and needed capacitance as well as voltage current and a number of other parameters from circumference, diameter of element, frequency and power, these are very useful modelling programs that will calculate for circulator, octagonal and square configurations. Loopcalc, RJELoop and magloop4 are three that I use.

The main issue in Mogadishu will be salt corrosion on the copper tube and capacitor, so I am using plastic coated Heliax which gives slightly different readings from the programs, I guess due to the dielectric effect on the plastic covering, of course that will provide corrosion protection, I have just bought a plastic lunch box/refrigerator box to put the vacuum variable and ends of the loop in to protect from the salt air. The antenna will only be about 300m from the water's edge and in the evenings there is a nice sea-breeze, cooling down everything but bringing lots of salt to corrode!

I have a Flex-1500 but unfortunately the Atom N570 powered netbook has just not got enough oomph to successfully run WSPR, PowerSDR, USB transfer AND decode the spots. Even just running the netbook and an analogue transceiver I do not get anywhere near the number of spots I get if I use the MacBook and the OS X compiled WSPR. To successfully run PowerSDR, WSPR, get USB working properly AND decode, I would probably need a quad core or even a Core i7 and 2-4GB of ram. I just wish PowerSDR was also written for OS X".

Great work Ross! That's a very nice vacuum variable capacitor you have there. I like the fire extinguisher close by.

Monday, February 06, 2012

MorseDec morse decoder for iOS

Here's a demo of a morse decoder that works pretty well. MorseDec.

A new version, 1.2, came out today that fixed a bug in the spectrum display. Here's it decoding the VK2WI morse beacon on 3.7MHz. This is simple acoustic coupling to the iPhone's microphone. It's 2:30 in the afternoon and there's a bit of fading so I think it's doing a pretty good job.

Getting to Neil Young's audio quality

Musician Neil Young's interview with Walk Mossberg at the recent All things D: Dive Into Media conference last week is worth a look.

Young says that in the studio he's pretty happy with masters recorded at "24/192" which is presumably 24 bit at 192kHz sample rate (lossless compression). He bemoans the fact that most listeners currently get "just 5%" of the music data in the form of MP3 compressed audio.

I think that's overstating it a little, while the file size might be 5%, the genius of lossy compression is that it doesn't sound 95% worse. Despite apparently having been working with the late Steve Jobs on bringing better quality to portable players, Young never mentions better codecs such as AAC which Apple standardised on, Apple Lossless or the freely available FLAC.

My setup here has a number of external USB audio devices and to find out what their capabilities are you use the "Audio MIDI Setup" app found in the Utilities folder. My day to day headphone driver is a Corda "Move":

Like the Mac's internal audio, it's capable of 16/48, but interestingly it was defaulted to 16/44.1. This probably makes sense as pretty much all my music is from CDs which are sampled at 16/44.1kHz. I have some uncompressed tracks, you can see them in iTunes by getting info:

Again the sample rate is 44.1kHz and the sample size is 16 bit. I would assume that matching the output DAC to the sample rate of the recording would avoid resampling errors and extra CPU effort.

Would a move to 24/192 make a big difference?

Sampling at 44.1kHz means that the theoretical highest frequency that can be reproduced is 22kHz but a tone at that frequency would end up being a square wave that would be low passed filtered back to a sine wave - no doubt bearing little resemblance to the original waveform except in frequency. While I certainly can't hear beyond about 15kHz these days, I'm confident that others, particularly teenagers, can. Going to 192kHz seems a big jump. Perhaps 96kHz would be a good next step.

24 bits instead of 16 doesn't seem like a huge leap and given that storage and bandwidth go up by a third every few months I can't see any reason not to go to 24 bit.

Compressed bit rate

The other part of the equation is the bit rate that lossy compression must fit the audio in to.

Apple made the move to 16/44.1 AAC at 128kbps in the iTunes store without being pushed a few years ago and one of the benefits of their cloud music system is that they give you a better version of your tracks if required. (AAC is better than MP3 and a bit rate of 128kbps AAC is generally agreed to be equivalent to 196kbps MP3).

My guess is that further increasing the compressed bit rate would give a greater improvement to the perceived audio than increasing sampling or sample size bits. Of course no lossy compression is where we need to get in the end.

High resolution source audio

Increasing the sample rate or sample size beyond the original that most of us deal with every day - Audio CDs, will not improve the audio. Short of original recordings, the only other widely available source of high quality audio are "Super Audio CD" (SACD). These are recorded at a sampling rate of 2.8224 MHz  and encoded as direct stream digital which is hard to directly compare with 16/44.1 but given the claimed high frequency response limit of 100kHz, seems more than twice as good, and arguably good enough for Neil Young. (It would be interesting to quiz him about this).

I found some 24/96 audio and was able to play it with VLC (although my USB DAC will only sample up to 48kHz):

Turns out I have an audio device capable of playing this without loss. It's an Edirol UA-25EX. Once the driver was installed it can do what we want:

It sounds pretty good, particularly the cymbal sounds I think, but to be honest at my age it's probably lost on me.

Pay for quality option

Another interesting thread in the interview was that "piracy is the new radio". He's talking about customer learning about new music by first getting a copy from someone and then going on to buy the tracks.

We already pay a little extra for an HD version of a movie, (and I always do pay the extra personally), it makes sense to offer more options including very cheap versions for small screens.

In the case of music, where it is often being consumed in noisy environments or simply as low level background, it might be good to have very low priced - (or even free) to a low bit rate, possibly compressed and equalised to suit the listening environment. There would be the opportunity to "upgrade" to a high resolution version.

Young's comment about it taking 30 minutes to download a decent quality version won't prevent piracy of these versions as it's clear that consumers currently download HD movies without much sweat and speed will relentlessly increase.

What really makes the difference to audio listening quality?

Before all of these upgrades, the first thing to upgrade is speakers/headphones and amplifier. I recently purchased a pair of Sony MDR-7506 headphones and have been very happy with them. Day to day I use a little headphone amplifier and have built several Chu Moy amplifiers that really sound great.

Young is kind of right but doesn't realise that our existing hardware is already capable of increased quality in the form of lossless support and slightly higher bit rates. I'd like to see sliding price scales for better quality digital audio so that those who want it can get it.

Discussion on RN Breakfast

We had a panel discussion on RN breakfast this morning. Got a big listener response which was great. Here's co-panelist, Robbie Buck, standing by for air on the "brefast" show:

We had a bit of fun and played a vinyl record and then an MP3 for the listeners, many of them on AM radios. Lots of emails from people preferring the vinyl version.

iTunes store accepts higher resolution audio

I've just read in “Music as the Artist and Sound Engineer Intended,” that iTunes has asked publishers to submit high-resolution 24-bit/96kHz files, and not original CD masters to create the 256kbps files which are sold as iTunes Plus tracks.

Great stuff!

Saturday, February 04, 2012

Ham radio day in Killarney Heights

The weather in Sydney has flipped back to sunny again. On the bench in the shack is an Ensemble RXTX software defined transceiver. Progress is slow but steady. After the WIA Sunday broadcast we had callbacks on 80m and there was some gear changing hands between Robert VK2ZNZ and Mal VK2BMS so I offered to be the taxi.

First we visited Mal's place to pick up some very well made gear. I learned that they would wind RF inductors with hot wire on to porcelain forms so that the wire would cool and contract and therefore hold tight.

Mal has a fine shack that looks out over a fantastic antenna tower in the back yard. He certainly puts a thumping signal in to my place just across the water.

Next we visited Rob's place.

We listened to the radio for a while.

And played a record. Surprisingly loud.

Mal and I headed off to Pet Barn to pick up supplies during their 20% off sale. We were joined there by NSW Premier Barry O'Farrell.

Wednesday, February 01, 2012

Ear piercing through cartilage ends in hospital

My daughter decided to get some new ear piercings a few weeks back. One went through cartilage near the top of her ear.

The ear went red and swelled up so much that the stud disappeared into the wound. Our GP had a go at getting it out but in the end sent us on to hospital emergency, which after the minor surgery, admitted her for forty eight hours.

Mona Vale Hospital did a great job, and it's much quieter than Royal North Shore (where I took my broken toe a few years back).

We've had a very good run with the kids and illness or injury. My daughter hasn't been to hospital since birth and there was some messing with computers to figure out that she had no entry in their database.

If your kids want piercings that go through cartilage you can tell them from us that getting them out after an infection is a very painful operation. Infected cartilage is less serious than a bone infection but still quite serious.